203786-48-5

Upstream product

• 203786-47-4 C₆₀H₆₈N₈O₁₃ 
• 203786-45-2 (R)-2-{(R)-2-[(9H-Fluoren-9-ylmethoxycarbonyl)-methyl-amino]-propionyl}-tetrahydro-pyridazine-1,3-dicarboxylic acid 3-benzhydryl ester 1-benzyl ester 
• 203786-46-3 (R)-3-(N'-tert-Butoxycarbonyl-hydrazinocarbonyl)-2-{(R)-2-[(9H-fluoren-9-ylmethoxycarbonyl)-methyl-amino]-propionyl}-tetrahydro-pyridazine-1-carboxylic acid benzyl ester 
• 203786-52-1 (R)-2-{(R)-2-[(9H-Fluoren-9-ylmethoxycarbonyl)-methyl-amino]-propionyl}-tetrahydro-pyridazine-1,3-dicarboxylic acid 1-benzyl ester 
• 908093-98-1 diazodiphenylmethane 

Relevant academic research and scientific papers

Total synthesis of 4-epi-A83586C. Epimerisation in a macrolactamisation mediated by BOP and DMAP

Protected linear hexapeptide 2 undergoes a remarkably facile C(4)-epimerisation when macrolactamisation is attempted with BOP [benzotriazol-1-yloxy-tris(dimethylamino)phosphonium hexafluorophosphate] and DMAP in CH2Cl2 under conditions of high-dilution; compound 6 is isolated in 51% yield from this reaction. In order to confirm its structure, 6 was independently synthesised from 18 by macrolactamisation with HATU [O-(7-azabenzotriazol-1-yl)-N,N,Nprime;,N′-tetramethyluronium hexafluorophosphate)] and NEM (N-ethylmorpholine); ring-closure now proceeded in 70% yield. After subsequent deprotection by catalytic hydrogenolysis, amine salt 7 was chemoselectively coupled to activated ester 5 to give 4-epi-A83586C (8) after glycal hydration.